Re: Hello from Cali! New here, and a complete n00b to this
Being new at this I can tell you what would have helped me out- it's still fresh in muh mind.
Get a steel frame with standard size frame tubes with plenty of room in the V, rims with 36 heavy gauge spokes, don't get sucked into any tires fatter than 2.2" or 55mm or a jackshaft you will be a-needing, solidly mount your engine and solder all your connections. Spring for tuffy tire liners if you hate walking like I do. Plan for and budget in some half way decent brakes (I still need one).
Do all that and you'll be way ahead of me when I started on my bike.
These guys know everything right down to which rod goes with which piston on the china dolls, if that is the engine you're planning to use.
There are many sharp 4 stroke riders, too.
You are in the right place to get it built smoothly, so feel free to ask.
Buzz zzzzz zzz